U.S. patent number 4,088,397 [Application Number 05/725,156] was granted by the patent office on 1978-05-09 for optical device comprising mechanical connections transverse to the optical path.
This patent grant is currently assigned to Etablissements Pierre Angenieux, Thomson-CSF. Invention is credited to Francis Jourdan, Charles Le Roux, Jean-Paul Lepeytre, Andre Masson.
United States Patent |
4,088,397 |
Jourdan , et al. |
May 9, 1978 |
Optical device comprising mechanical connections transverse to the
optical path
Abstract
An optical device comprising at least an optical element having
a cut away area and which supports an inner mechanical structure
accommodated in the cut away area, the whole being supported by an
outer mechanical structure without obstruction in the optical path
between the structures. The contact areas of the optical element
with the structures comprise mechanical gripping and position means
including deformable members for holding an unvaried centered
position to the optical element for severe temperature and
mechanical operating conditions.
Inventors: |
Jourdan; Francis (Paris,
FR), Lepeytre; Jean-Paul (Paris, FR),
Masson; Andre (Paris, FR), Le Roux; Charles
(Paris, FR) |
Assignee: |
Thomson-CSF (Paris,
FR)
Etablissements Pierre Angenieux (Paris, FR)
|
Family
ID: |
9160388 |
Appl.
No.: |
05/725,156 |
Filed: |
September 21, 1976 |
Foreign Application Priority Data
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Sep 24, 1975 [FR] |
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75 29265 |
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Current U.S.
Class: |
359/820;
359/808 |
Current CPC
Class: |
G02B
7/026 (20130101); G02B 17/0808 (20130101); G02B
17/0884 (20130101) |
Current International
Class: |
G02B
17/08 (20060101); G02B 7/02 (20060101); G02B
007/02 () |
Field of
Search: |
;350/201,199,200,252,253,187 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Sacher; Paul A.
Attorney, Agent or Firm: Cushman, Darby & Cushman
Claims
What is claimed is:
1. An optical device comprising: at least one optical element
having a cut-away area along the optical axis, an outer mechanical
structure for supporting peripherally the said optical element, an
inner mechanical structure accommodated in said cut-away area and
secured to the outer structure by mechanical connections, said
connections being formed by said optical element and mechanical
gripping and positioning members arranged in the respective contact
between the optical element and the said structure to provide any
obstruction along the optical path, comprised between the said
structure, the said mechanical gripping and positioning members
comprising deformable elastic members for holding substantially an
unvaried centered position to said optical element for
predetermined severe temperature and mechanical operating
conditions, the said deformable members comprising, in each contact
zone, at least one mechanical part provided with deformable arcuate
segments against which sad optical element bears.
2. An optical device according to claim 1, comprising a combination
of optical elements in which a said optical element is cut-away in
its central portion, the said mechanical deformable members
comprising, in the case of both structures, a cylindrical part
provided with two sets of regularly distributed slots and with
recessed areas to form the said arcuate bearing segments.
3. An optical device according to claim 2, wherein the said
cut-away optical element forms the optical input element of the
said optical combination, and wherein the said mechanical gripping
and positioning members include seals, for isolating an external
ambient medium from an internal medium.
4. An optical device according to claim 2, wherein the said
mechanical gripping and positioning members include at least one
washer which bears laterally against the said cut-away optical
element, the said washer being made of a plastics material of
predetermined elasticity.
5. A device according to claim 1, comprising an optical combination
catadioptic system formed by at least one cut-away lens supporting
a first inner structure, a main cut-away mirror supporting a second
inner structure, a secondary mirror supported by the first inner
structure, and at least one lens supported by the second inner
structure, the said first mechanical structure supporting the said
optical combination by said mechanical connections comprising the
said first lens and the said main mirror.
Description
The present invention relates to an optical device in which a
plurality of separate mechanical structures are to be joined
together by mechanical connections passing through the optical
path.
In such devices the mechanical connections in question are
determined so that the obstruction which they cause to the optical
combination utilized is rendered as small as possible. In this way,
it is possible for the optical performance of the device to remain
substantially unaffected.
This problem particularly exists with optical systems which
comprise optical elements partly cut-away, generally at the centre,
to accommodate an inner structure which, together with the optical
elements themselves, is supported by an outer structure.
The solution generally adopted consists in effecting the
connections by means of arms or spokes whose shape or dimensions
are calculated to provide both the requisite mechanical strength
under the planned operating conditions and also very little
obstruction to the optical beam. Consequently, the thickness of
these mechanical members in a plane transverse to that of the
optical path is made as small as possible.
When the conditions under which operations have to take place are
severe, in particular from the point of view of resistance to
temperature, impacts and vibrations, sturdy mechanical connections
have to be provided and the obstruction which these cause may be a
hindrance from the point of view of the performance which is
required from the optical combination in other respects.
An object of the invention is to provide an optical device which
solves this problem by making use of one or more optical elements
of the optical combination which, whilst continuing to perform
their appointed optical function in the same way, further perform
the function of providing mechanical connections between the
various structures.
According to the invention, there is provided an optical device in
which mechanical connections transverse to the optical path are to
be provided, said optical device comprising: at least one optical
element for providing said optical path and comprising a partly
cut-away area, a first mechanical structure external to said
optical path and supporting the said optical element, and at least
a second mechanical structure accommodated in said cut-away area
and secured to the first structure by said mechanical connections,
said optical element comprising respective contact zones with the
said structures arranged with mechanical gripping and positioning
members.
The invention will now be further described with reference to the
accompanying drawings, in which:
FIGS. 1 and 2 are simplified diagrams which illustrate,
respectively, a type of optical device to which the invention
relates and the principle utilized,
FIGS. 3 to 6 show sections through part of an embodiment as shown
in FIG. 2, and
FIG. 7 shows schematically an embodiment of an optical system which
comprises mechanical connections provided according to the
invention.
An optical device of the type concerned, which is shown
schematically in FIG. 1, has a first mechanical structure 1 to
support one or more elements of the combination.
For reasons of simplicity, only one optical element 2 is shown in
the diagram. One or more other mechanical structures, such as 3 and
4, which are separate from structure 1, are generally provided to
support other optical elements belonging to the combination which
are not shown. Structures 3 and 4 are arranged in cut-away areas of
optical element 2 and need to be secured to structure 1 to ensure
that the optical elements forming the combination are accurately
positioned relative to one another.
The mechanical connections which are required between structures 3,
4 and structure 1 are produced by making use of the optical means 2
and for this reason do not in any way obstruct the optical
combination. The areas of contact between the optical means 2 and
the structures 1, 3 and 4 are arranged accordingly. These areas are
shown at 5 and 6 in FIG. 2, which relates to a simplified example
of an optical device only part of which is shown and which
incorporates a lens 2. The lens 2 is supported by an outer
structure 1 and supports an inner structure 3 which is located in a
cut-away central area of the lens.
Areas 5 and 6 are arranged particularly to take account of the
differing nature of the materials in contact, of the accuracy to be
observed in their relative positions, and of the climatic and
mechanical environmental conditions in which the device is required
to operate.
An embodiment corresponding to the partial diagram in FIG. 2 is
shown in the succeeding FIGS. 3 to 6.
The optical element 2 is centered in the outer structure 1 and is
held in position by a mounting ring formed by two parts 10 and 11,
a pressure washer 12 and a nut 13. Element 2 is clamped by
tightning nut 13. The mounting ring contains seatings to hold
O-rings 14, 15 and 16 on the side on which the external structure 1
is situated and these O-rings form a seal around the circular
periphery of the optical element 2 between the media A and B
situated on either side of it. Medium A may for example be the
ambient external medium and medium B an internal medium in the
piece of equipment. The connecting members need to ensure that the
optical element 2 is held in place correctly and without damage
when the environmental temperature conditions are likely to vary
over a wide range such as -55.degree. to +70.degree. C. For this
purpose, the washer 12, whose bearing face applied to element 2 is
matched to the shape of the latter, is made of a material having
appropriate mechanical characteristics to enable the changes which
occur in the dimensions of the parts in the planned temperature
range to be taken up by elastic deformation. The pressure washer 12
may in particular be made from a plastics material. Also, part 10
of the mounting ring is provided with slots 17 which are situated
opposite a circular recess 18 in structure 1. FIG. 5 is a partial
cross-section through part 10 in a plane of section P which passes
through a slot 17. Part 10 contains two sets of eight regularly
distributed slots and internal recessed portions 9, which give it a
certain degree of elasticity which it requires, particularly at low
temperatures, in order to be able to take up the changes in the
dimensions of the metal parts 1 and 10 without risk of damage to
the optical element 2. The variations in the dimensions of the
metal parts 1 and 10 are greater than those experienced by element
2, which is made of glass, and they result in a constrictive
pressure on the optical element as a result of a reduction in the
diameter D1 defining the centered position i.e. the position of the
optical axis Z. The slots define eight arcuate segments 19 which
are diametrically opposed in pairs and which are able to deform
elastically to take up the variations in diameter which occur at
low temperatures and to hold the constrictive pressure at an
acceptable level which does not cause damage to the optical
element. The outer periphery of the latter bears against the
arcuate segments 19 of part 10, with the slots 17 and the recessed
portions 9 lying outside the supporting areas (CD FIG. 5). The
dimensions of the slots and the arcuate segments are so calculated
that the deformations which have to be accepted are compatible with
the limiting elastic characteristics of the material forming part
10 of the mounting ring. Thus, the special provisions made by
selecting the material of part 12 and by providing the deformable
arcuate segments of part 10 result in resilient connecting means
which enable the optical element to be held in position and thus
centered without risk of damage under the severe environmental
conditions to which it is subject. FIGS. 3 and 4, are respectively,
a section in a section-plane X passing through the area in which
the slots are situated and a section in a section-plane Y away from
the slots.
The connections to the inner structure 3 are produced in a similar
way and are shown in FIGS. 3, 4 and 6. Structure 3 is centered by
and bears against optical element 2. Lateral support is provided by
tightening a nut 20 and by means of a washer 21, one face of which
follows the shape of the front surface of lens 2. Part 22 forms a
sealing cap on the side of the inner structure 3 on which medium A
is situated. A seal between media A and B is provided by O-rings 23
and 24. Diametric support for optical element 2 is provided as
above by arcuate segments 25 (EF in FIG. 6 which is a vertical
section in plane R through a slot 26). The segments 25 are
delimited by an array of slots 26 and recessed portions 27 (FIG.
4). Since parts 2 and 3 are made of different materials, one being
made of glass and the other of metal, temperature variations affect
them differently. At high temperatures, the variations in the
centering diameter D2 is a result of expansion, which is greater
for the inner structure 3, is absorbed without danger to the lens 2
by deformation of the inner structure, which contains slots 26 and
recessed portions 27 between successive arcuate segments 25. The
elastic deformation which occurs following a rise in temperature
restricts pressure on the optical element 2 in a direction
transverse to the optical axis to a level which the latter is able
to withstand.
The combined action of the members which connect the optical
element 2 to structures 1 and 3 enable the optical axis Z of
element 2 to be held in the correct position under the mechanical
and climatic environmental conditions which are anticipated, the
optical element 2 supporting the inner structure 3.
FIG. 7 shows an application of the optical device to a catadioptric
system in which the optical combination comprises two lenses 2 and
33 and two mirrors 30 and 31. The secondary mirror 30 is supported
by the inner structure 3. The main mirror 31 carries a second inner
structure 32 which in turn supports lens 33. The mechanical
connections between optical element 31 and structures 1 and 32 are
produced in a similar way to those described above in the case of
assembly 1, 2 and 3.
In the optical device described, the mechanical means which provide
the transverse connections required between the various structures
to be connected are made of a transparent material, which, in the
optical path of the light radiation, is formed by the material of
the optical elements belonging to the optical combination. For this
reason, there is no additional obstruction from these mechanical
means other than that which inevitably arises from inner structures
situated in the cut-away parts of the optical elements. In a system
of the type shown in FIG. 7, the sole cause of partial obstruction
is the inner entry structure 3. For reasons of simplicity, the
optical connecting members shown in the Figures have been
restricted to a single optical element whose centre is cut-away but
it is understood that this element could be a plurality of elements
and as an example elements 2 and 33 (FIG. 7) could each consist of
a group of lenses. It is like-wise understood that not all the
inner structures have necessarily to support one or more optical
elements of the combination and they may be used for other
purposes.
Of course the invention is not limited to the embodiment described
and shown which was given solely by way of example.
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